"I'm not a religious person." In my 30+ years of ordained life, I've had many people say that to me. Often it was an "explanation" of why they didn’t attend church. After all, attending church is for people who are religious. It's certainly not a place for the non-religious, the unreligious, the irreligious, the I-don’t-know-what-I-think-about-religion folk.
And when most of these good folk would claim not to be religious, they probably were also hinting at their inner conviction that the record of their lives would not stand up to the standards they assumed were required for those who are religious and/or attend church. The church, of course, is also not a place for those who've messed up or who are in the act of messing up their lives. As Mark Twain claimed, "The church is a place where a nice respectable person stands up in front of other nice respectable people and urges them to be nicer and more respectable."
Often when someone would tell me that he/she was not religious, I'd reply, "Neither am I." This would almost always evoke surprise and even laughter. How can I be a priest and not be religious? In fact, the clergy are usually expected to personify all the religious characteristics. Aren't they?
I could probably answer that question better if there were any satisfactory definition of the word religious. Like the term Christian, and the term Church, there are as many understandings as there are people. The Ontario Consultants on Religious Tolerance have an article on definitions of religion: Definitions of the word "religion"(None are totally satisfying). They settled on what they call their compromise definition.
"This website's essays use a very broad definition of religion:
"Religion is any specific system of belief about deity, often involving rituals, a code of ethics, a philosophy of life, and a worldview." "
I do have a belief about deity, I'm often involved in rituals, I do have a code of ethics, a philosophy of life and a worldview. But probably so do all those people who claim not to be religious. If to be religious is what I think most people who've claimed not to be believe it is: to be nice, respectable and good, to not have ever messed up your life, to never have questioned your belief in deity, or dropped away from being involved in the rituals, or transgressed your own code of ethics, wondered about your philosophy of life, or changed your worldview from time to time, then I'm not religious and I hope I never am.